package TreeNode;

import java.util.*;

public class Solution {
	public List<Integer> postorder(TreeNode root) {
		if(root == null) return new ArrayList<>();
		List<Integer> list = new ArrayList<>();
		list.addAll(postorder(root.left));
		list.addAll(postorder(root.right));
		list.add(root.val);
		return list;
	}
}
